阅读说明：本技术 基于高温和碳化耦合的再生水泥的制备方法和应用 (Preparation method and application of regenerated cement based on high temperature and carbonization coupling ) 是由 王俊杰 李克非 李乐 于 2021-09-27 设计创作，主要内容包括：本发明公开了一种基于高温和碳化耦合的再生水泥的制备方法和应用。其中方法包括：将水泥浆体进行碾磨,碾磨后,在水和二氧化碳存在下,采用扬粉形式进行高温碳化耦合处理；高温碳化耦合处理后,在高温下进行干燥处理；干燥处理后,急速冷却至100℃以下,进行二次碾磨,得到再生水泥。本发明制备得到再生水泥,有助于实现固碳效果,可以推动建筑垃圾的资源化利用,具有节能减排的优点。(The invention discloses a preparation method and application of regenerated cement based on high temperature and carbonization coupling. The method comprises the following steps: grinding the cement paste, and then carrying out high-temperature carbonization coupling treatment in the presence of water and carbon dioxide in a powder raising mode; after the high-temperature carbonization coupling treatment, drying treatment is carried out at high temperature; drying, quickly cooling to below 100 deg.C, and grinding again to obtain regenerated cement. The recycled cement prepared by the method is beneficial to realizing the carbon sequestration effect, can promote the resource utilization of construction waste, and has the advantages of energy conservation and emission reduction.)

1. A preparation method of recycled cement based on high temperature and carbonization coupling is characterized by comprising the following steps:

step S20, grinding the cement paste, and then carrying out high-temperature carbonization coupling treatment in the form of raising powder in the presence of water and carbon dioxide, wherein the high-temperature is 400-650 ℃;

step S30, drying at 400-650 deg.C after high temperature carbonization coupling treatment;

and step S40, after drying, rapidly cooling to below 100 ℃, and carrying out secondary grinding to obtain the recycled cement.

2. The method for preparing recycled cement based on high temperature and carbonization coupling as claimed in claim 1, wherein in step S20, blowing high temperature gas with humidity of 30% -90% by blower for raising powder, and CO in the gas₂The concentration is 0.5-30%.

3. The method for preparing recycled cement based on high temperature and carbonation coupling according to claim 1, wherein said drying process is an oven drying process in a humidity of 0% at step S30.

4. The method for preparing recycled cement based on high temperature and carbonation coupling according to claim 2, wherein in step S20, the temperature of the air blown by the blower is 450 ℃, the humidity is 75%, and the CO is introduced₂The concentration is 20%; in step S30, the temperature is maintained at 450 ℃ and the drying process is performed.

5. The method for preparing recycled cement based on high temperature and carbonation coupling according to claim 1, wherein in step S20, grinding to size < 150 μm; in step S40, the secondary grinding is carried out until the size is less than 150 μm.

6. The method for preparing recycled cement based on high temperature and carbonation coupling according to claim 1, further comprising: and step S10, taking the waste building rubbish as a raw material, and separating bone cement to obtain cement paste.

7. The method for preparing recycled cement based on high temperature and carbonation coupling according to claim 6, wherein step S10 comprises:

step S11, sorting waste concrete and waste mortar from waste construction waste, and crushing the waste concrete and the waste mortar to obtain small particles with the size less than 5 mm;

step S12, performing ball milling at 400-600 ℃, and rapidly cooling to below 100 ℃ after ball milling;

and S13, screening the ground balls by a fan to obtain machine-made reclaimed sand and cement slurry, wherein the machine-made reclaimed sand is used for preparing finished concrete or finished mortar.

8. The method for preparing recycled cement based on high temperature and carbonation coupling according to claim 7, wherein step S12 further comprises: sampling and detecting, and judging whether the cement slurry on the surface of the machine-made reclaimed sand is completely ground off, if so, performing step S13, otherwise, returning to step S12.

9. Use of a recycled cement for the preparation of finished concrete or mortar, characterized in that it is obtained by using the method for the preparation of recycled cement based on high temperature and carbonation coupling according to any one of claims 1 to 8.

10. The use of claim 9, wherein when the recycled cement is used for preparing finished concrete or mortar, the raw materials further comprise machine-made recycled sand and an additive, wherein,

the machine-made reclaimed sand is prepared by the preparation method of the reclaimed cement based on high temperature and carbonization coupling according to claim 7;

the additive comprises one or more of mineral admixture, water reducing agent and retarder, and the mineral admixture is granulated blast furnace slag and/or fly ash.

Technical Field

The invention relates to the technical field of preparation of recycled cement, in particular to a preparation method and application of recycled cement based on high temperature and carbonization coupling.

Background

The construction waste refers to the general term of dregs, waste concrete, waste bricks and stones and other wastes generated in the production activities of the construction industry such as demolition, construction, decoration and repair, and is classified according to the composition, and the construction waste can be divided into dregs, waste concrete blocks, broken stones, broken bricks and tiles, waste mortar, slurry, asphalt blocks, waste plastics, waste metals, waste bamboo and wood, and the like. At present, the yield of the construction waste accounts for a relatively large amount in the total amount of the urban waste, which accounts for about 30% -40% of the total amount of the urban waste, and the construction waste is treated by direct landfill or accumulation in a relatively large manner, so that the resource utilization rate of the construction waste is very low. Therefore, with the continuous expansion of the construction industry, research and popularization of construction waste recycling are imperative.

In the prior art, the Chinese application publication No. CN1857782A discloses a method for separating waste concrete components, and provides a method for producing recycled aggregate and recycled cement by using waste concrete, the method calcines the waste concrete at the temperature of 750-800 ℃, and prepares the recycled cement by using cement paste after separating the recycled aggregate by using a mechanical separation method. However, the above-mentioned methods do not achieve the properties of portland cement and cannot replace portland cement 100%, and in addition, the methods increase carbon emissions due to too high temperatures.

The Chinese application publication No. CN101948280A discloses a method for preparing building mortar by using waste concrete, and particularly discloses that the concrete is calcined for 5-10 hours at 350-750 ℃, and concrete powder crushed by an Escherchia crusher is added into a ball mill for dry grinding, so that the regenerated cement obtained by the method can not reach the performance of common cement and can not replace the common cement by 100 percent, and in addition, because the content of calcium oxide is too high, the subsequent use can become hidden danger.

Therefore, in the method for recycling the building waste in the prior art, the prepared recycled cement has poor performance and cannot completely and truly replace the common cement, and the problems of high temperature, environment and the like in the preparation process are solved.

On the other hand, the present inventors recognized that: at present, the carbon dioxide concentration in the air is increased day by day in the global range, which causes serious consequences of climate change, and the cement production is one of the factors for increasing the carbon dioxide concentration in the global range. Therefore, the cement industry is taken as a high-energy-consumption and high-pollution industry, and measures for reducing the emission of greenhouse gases are imminent.

Disclosure of Invention

Based on the above, the invention aims to provide a preparation method and application of regenerated cement based on high temperature and carbonization coupling, so as to prepare the regenerated cement, facilitate the realization of carbon sequestration effect and promote the resource utilization of construction waste.

The above purpose of the invention is realized by the following technical scheme:

according to one aspect of the invention, the invention provides a preparation method of recycled cement based on high temperature and carbonization coupling, which comprises the following steps:

step S20, grinding the cement paste, and then carrying out high-temperature carbonization coupling treatment in the form of raising powder in the presence of water and carbon dioxide, wherein the high-temperature is 400-650 ℃;

step S30, drying at 400-650 deg.C after high temperature carbonization coupling treatment;

and step S40, after drying, rapidly cooling to below 100 ℃, and carrying out secondary grinding to obtain the recycled cement.

Optionally, in step S20, blowing high-temperature gas into the furnace by a blower to raise powder, wherein the humidity of the gas is 30% -90%, and the CO in the gas is₂The concentration is 0.5-30%.

Optionally, in step S30, the drying process is performed by oven drying in an environment with a humidity of 0%.

Optionally, in step S20, a blower is used to lift the powder, and the temperature of the gas blown in by the blower is 450 ℃, the humidity is 75%, and CO is present₂The concentration is 20%; in step S30, the temperature is maintained at 450 ℃ and the drying process is performed.

Optionally, in step S20, milling to a size < 150 μm; in step S40, the secondary grinding is carried out until the size is less than 150 μm.

Optionally, the method further includes: and step S10, taking the waste building rubbish as a raw material, and separating bone cement to obtain cement paste.

Further, step S10 includes: step S11, sorting waste concrete and waste mortar from waste construction waste, and crushing the waste concrete and the waste mortar to obtain small particles with the size less than 5 mm; step S12, performing ball milling at 400-600 ℃, and rapidly cooling to below 100 ℃ after ball milling; and S13, screening the ground balls by a fan to obtain machine-made reclaimed sand and cement slurry, wherein the machine-made reclaimed sand is used for preparing finished concrete or finished mortar.

Optionally, in step S12, the method further includes: sampling and detecting, and judging whether cement slurry on the surface of the machine-made reclaimed sand is completely ground off, if so, performing step S13, otherwise, returning to step S12 for ball milling.

According to one aspect of the invention, the invention provides application of the recycled cement in preparation of finished concrete or mortar, wherein the recycled cement is prepared by the preparation method of the recycled cement based on high temperature and carbonization coupling.

Optionally, when the recycled cement is used for preparing finished concrete or mortar, raw materials further comprise machine-made recycled sand and an additive, wherein the machine-made recycled sand is synchronously produced by the preparation method of the recycled cement based on high temperature and carbonization coupling; the additive comprises one or more of mineral admixture, water reducing agent and retarder, and the mineral admixture is granulated blast furnace slag and/or fly ash.

Compared with the prior art, the method disclosed by the invention has the advantages that the recycled cement is prepared based on high temperature and carbonization coupling, the performance is excellent, the recycled cement can replace the common cement, the carbon fixation effect is realized, the resource recycling of the construction waste is promoted, and the energy saving and emission reduction effects are realized.

The invention has the advantages that the invention also can be embodied in the following aspects:

1) the raw material of the cement slurry for preparing the recycled cement can be cement slurry prepared by sorting and ball-milling construction waste, can also be pure cement slurry blocks, and has wide application range.

2) The regenerated cement produced by the invention has the characteristics of carbon sequestration, energy conservation, emission reduction and the like.

3) The machine-made reclaimed sand obtained by synchronous production through high-temperature ball milling and rapid cooling is high-quality machine-made reclaimed sand, has physical and chemical properties similar or identical to those of natural sand, and does not have cement paste on the surface.

4) According to the invention, the treatment mode and various parameters in the high-temperature carbonization coupling treatment process are optimized, so that the stability of the reaction product is improved, the full reaction is ensured, and the carbon fixation effect is fully realized.

5) The invention increases the activity of the recycled cement through the oven-dry environmental treatment, the rapid cooling and the secondary grinding, thereby being beneficial to improving the application effect of the recycled cement, namely improving the quality of the prepared finished concrete or mortar.

Drawings

FIG. 1 is a schematic flow diagram of the method for preparing reclaimed cement based on high temperature and carbonation coupling according to the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a preparation method of recycled cement based on high temperature and carbonization coupling, which comprises the following steps: grinding the cement slurry, coupling treatment of high temperature and carbonization, oven drying treatment, quenching and secondary grinding to obtain the regenerated cement. The cement slurry is a pure cement slurry block, or the cement slurry is prepared by taking construction waste as a raw material and performing sorting crushing, mortar separation and fan screening. The regenerated cement prepared by the invention can be applied to the preparation of finished concrete or finished mortar by adding additives.

Fig. 1 schematically shows a process for preparing recycled cement based on high temperature and carbonization coupling and the application thereof in an embodiment of the present invention, in which cement paste is prepared from construction waste by sorting and ball milling, and a method for extracting recycled cement from waste concrete and mortar. As shown in fig. 1, a preparation method and application of recycled cement based on high temperature and carbonization coupling comprises the following steps:

1) sorting and crushing:

firstly, recyclable waste concrete and recyclable mortar are sorted from construction waste, and other impurities are removed to obtain high-quality waste concrete and high-quality waste mortar so as to avoid influencing the subsequent process, wherein the impurities comprise all other impurities except the concrete and the mortar, such as reinforcing steel bars, coating, soil, plastics and the like.

And then, crushing the sorted waste concrete and mortar by a machine to obtain small particles with the size of less than 5mm, wherein the small particles are the machine-made reclaimed sand containing the cement paste. Wherein, can adopt jaw breaker or other similar machines, in order to avoid dust pollution, preferably adopt wet process crushing, adopt the mode of spraying in the crushing process. Furthermore, the water supply amount in the wet crushing process needs to be controlled, and the water supply amount is enough to ensure that the dust can be controlled, so that the ultra-fine powder is prevented from being taken away due to too much water.

2) And (3) mortar separation:

and then carrying out mortar separation, namely separating out the cement slurry on the surface of the machine-made reclaimed sand. The mortar separation may specifically include: performing ball milling at 400-600 ℃, wherein the particle size of the milling ball is not less than 6mm, the milling ball is convenient to be distinguished from mortar, and performing rapid cooling after the ball milling is finished to be cooled to below 100 ℃. According to the invention, the method of high-temperature ball milling and rapid cooling is adopted according to different temperature deformation coefficients of the cement paste and the machine-made reclaimed sand, so that the machine-made reclaimed sand and the cement paste are easy and thorough to peel. The rapid cooling in the step and the step 5) of the invention can be carried out by adopting a grate cooler, thus achieving the effect of effectively recovering heat energy.

Further, whether the ball milling effect reaches the standard or not can be judged through sampling detection. Specifically, after the sand is rapidly cooled to be below 100 ℃, part of samples are extracted to carry out mortar separation effect detection and judge whether the sand reaches the standard, and the standard of the standard is that all cement slurry on the surface of all machine-made reclaimed sand is ground off. And if the standard is not met, returning to perform mortar separation continuously.

Optionally, during ball milling, the feeding amount is controlled to be less than or equal to 1 in the material/ball mass ratio each time: 1, the ball body is made of wear-resistant and high-temperature-resistant Al₂O₃The material has uniform particle size distribution. The ball milling method (namely, the cement slurry on the surface of the machine-made reclaimed sand is milled off), the grain diameter of the grinding balls is preferably uniformly distributed in a range of 6-20 mm, so that the grinding balls and the machine-made reclaimed sand can be distinguished conveniently, and the problem that the grinding balls and the material are not easily distinguished if a grain diameter range overlapped with the machine-made reclaimed sand is used is avoided.

3) Screening by a fan:

after the mortar is separated, the grinding balls are separated for recycling; and then automatically screening by a fan under the action of wind power to obtain the machine-made reclaimed sand and cement paste. According to the embodiment of the invention, the machine-made reclaimed sand with high density and the cement paste with low density are quickly and conveniently separated from each other under the action of wind power according to the difference of the densities of the machine-made reclaimed sand and the cement paste.

In the step of automatically screening by the fan, an electric control fan screening machine or other machines with similar functions can be adopted. According to different densities and particle sizes, grinding balls, machine-made reclaimed sand and cement paste fall into different area ranges under the blowing of wind power of a fan; wherein, the grinding ball is withdrawn for repeated use; the machine-made reclaimed sand is a finished product material and can be directly stored for later use; and the cement paste is continuously milled and subjected to subsequent high-temperature carbonization coupling treatment. The machine-made reclaimed sand is sand which is obtained by synchronous production of bone cement separation and has the surface without cement paste, the size is less than 5mm, the machine-made reclaimed sand has high quality, the machine-made reclaimed sand has physical and chemical properties similar or identical to natural sand, and no cement paste exists on the surface. The high-quality machine-made reclaimed sand can be directly used as a finished product to be applied to the preparation of finished concrete or mortar through trial assembly.

4) Grinding treatment and high-temperature carbonization coupling treatment:

and then grinding the cement paste obtained by separating the bone paste, and performing high-temperature and carbonization coupling treatment. Wherein, the grinding can be carried out at room temperature, and can be carried out immediately after the cement slurry is discharged, for example, the interval time is not more than 1min, and the grinding can be carried out by adopting a wear-resistant machine. The invention can effectively activate the inside of the regenerated cement powder by immediately carrying out high-temperature carbonization coupling treatment on the ground cement paste, so that the regenerated cement powder has hydration activity again, and simultaneously, the content of free calcium oxide is reduced, and the stability of the regenerated cement is improved.

The conditions of the high-temperature carbonization coupling treatment are as follows: in the presence of water and carbon dioxide, high-temperature carbonization coupling treatment is carried out in a powder raising mode. The high temperature may be 400 to 650 ℃, for example, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, or the like. High-temperature gas can be blown in by a fan to carry out powder raising, and the humidity of the gas can be 30-90 percent, such as 40 percent, 60 percent, 75 percent, 85 percent and the like; CO in gas₂The concentration may be 0.5% to 30%, for example, 1%, 5%, 10%, 20%, 30%, or the like. In the preferred embodiment, a fan is adopted to blow in high-temperature gas and raise powder, so that the contact area of cement paste with water vapor and carbon dioxide is increased, the chemical reaction is facilitated, and the reaction is ensured to be more sufficient; and the reaction product can be stably existed in the high-temperature environment. According to the invention, the coupling range of the parameters of high temperature, water vapor content and carbon dioxide concentration is controlled, so that various performances of the recycled cement are improved, and the carbon sequestration effect is improved; if the temperature exceeds the range, the activity of the regenerated cement is reduced or the regenerated cement loses activity, and if the water vapor content or the carbon dioxide concentration exceeds the range, the problems of insufficient carbonization, carbon fixation failure or the coagulation of the regenerated cement into small blocks, unstable hydration of the regenerated cement and the like are caused.

In an alternative embodiment, the milling and high temperature carbonization coupling process may include the steps of: first, the cement slurry is milled to<150 μm; then blowing in CO with the humidity of 75% and the temperature of 450 ℃ by a fan₂Performing high-temperature carbonization treatment in an environment with a concentration of 20%. The reaction time of the high-temperature carbonization coupling treatment in the invention can be 5 sec-30 min according to the contact degree and reaction effect of the fugitive powder and the high-temperature reaction wind, and preferably, the reaction time is 15 min.

In this alternative embodiment, calcium hydroxide is completely decomposed at 450 ℃ into calcium oxide and water, the calcium oxide being in the presence of water and CO₂In the presence of calcium carbonate, which can be present very stably at this temperature. The environment with high temperature and carbonization coupled is 450 ℃, the humidity is 75 percent, and CO is₂The condition of 20 percent of concentration can more effectively ensure that all calcium hydroxide is completely decomposed and converted into calcium carbonate.

5) Oven drying treatment, quick cooling and secondary grinding:

after the high-temperature carbonization coupling treatment, keeping the high temperature of the previous step unchanged, for example, keeping the temperature of 450 ℃, and performing a drying treatment, preferably, performing an oven drying treatment in an environment with a humidity of 0%, so as to remove all free water; then rapidly cooling to below 100 ℃, and then carrying out secondary grinding to increase the activity of the regenerated cement, thus obtaining the finished product regenerated cement, wherein the regenerated cement is superfine regenerated cement powder obtained by high-temperature and carbonization coupling treatment, absolute drying treatment and grinding technology.

The detection shows that the recycled cement obtained by the invention has the following excellent properties: under the condition that the water cement ratio is 0.55, the strength of the regenerated cement slurry can reach more than 23MPa in 7 days, and the strength can reach more than 29MPa in 28 days. The recycled cement prepared by the invention can replace common cement, has a good carbon sequestration effect, promotes the resource utilization of construction waste, and has the advantages of energy conservation and emission reduction.

It is emphasized that the high temperature carbonization coupling treatment is performed under sufficient steam to ensure effective carbonization, and the oven drying treatment requires drying the free water content of the product to prevent inactivation of the regenerated cement, and thus the reaction chamber of the high temperature carbonization coupling treatment is effectively separated from the oven drying treatment chamber to prevent mutual influence.

6) The application comprises the following steps:

after the steps are completed, the recycled cement is obtained, the high-quality machine-made recycled sand is obtained through synchronous production, and the machine-made recycled sand and the recycled cement are applied to preparation of finished concrete or mortar, so that the effects of recycling construction waste, saving energy and reducing emission are achieved. In addition, the prepared new pouring concrete or mortar is dismantled after the service is finished, and can be recycled through the steps.

When the material is applied, the proper mixing ratio is determined through tests so as to avoid different quality of final products caused by different material sources; and then according to the determined mixing proportion, adding additives into the regenerated cement and/or the machine-made regenerated sand to prepare the finished concrete or mortar. The addition of the additive can improve the working performance and the setting performance of the recycled cement and concrete, the additive can comprise one or more of a mineral admixture, a water reducing agent and a retarder, and the mineral admixture is granulated blast furnace slag and/or fly ash. Further, the mineral admixture may be 10% to 65%, preferably 35% granulated blast furnace slag powder by mass of the gel material.

In the embodiment of the invention, waste garbage is used as a raw material, cement slurry is screened by adopting a sorting, crushing, high-temperature ball milling, rapid cooling and a fan, and the cement slurry is milled, subjected to high-temperature and carbonization coupling treatment, subjected to absolute drying treatment, and subjected to rapid cooling again and secondary milling, so that small waste concrete and small mortar are subjected to bone-slurry separation to obtain recycled machine-made recycled sand and recycled cement, and the machine-made recycled sand and the recycled cement can be applied to preparation of finished concrete and mortar, thereby achieving recycling of construction garbage, energy conservation and emission reduction; in addition, the high-temperature carbonization coupling treatment time has the carbon fixation effect, and the method has the characteristics of energy conservation and emission reduction. The method can be directly used on the construction waste removal site or adopted in a concrete commodity station.

The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to practitioners skilled in this art. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.